From Anger at MIT.EDU  Tue Jan  6 23:34:03 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Tue, 06 Jan 2009 23:34:03 -0500
Subject: [J-learn] Fwd: j installed on Athena
Message-ID: <20090106233403.27y3tzw79hk4kw4o@webmail.mit.edu>

----- Forwarded message from alexp at MIT.EDU -----
    Date: Tue, 06 Jan 2009 14:36:03 -0500
    From: Alex T Prengel <alexp at MIT.EDU>
Reply-To: Alex T Prengel <alexp at MIT.EDU>
 Subject: j installed on Athena
      To: software-announce at mit.edu

I've installed j on Athena for Linux machines. j is a sophisticated
mathematical programming language/development environment with full
graphics and animation capabilities. It is a kind of synthesis of the
older APL language with FP and FL function-level languages.

To run the GUI development environment:
   add j
   jwd

To run demos select Studio -> Demos. There is online help, and pdf
documentation starting from http://web.mit.edu/afs/athena/software/j_v602/

                                             Alex
----- End forwarded message -----


From Anger at MIT.EDU  Wed Jan  7 11:23:47 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Wed, 07 Jan 2009 11:23:47 -0500
Subject: [J-learn] Sessions 1&2 notes
Message-ID: <20090107112347.zaqfugrwo2r4swoc@webmail.mit.edu>


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From Anger at MIT.EDU  Thu Jan  8 23:52:28 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Thu, 08 Jan 2009 23:52:28 -0500
Subject: [J-learn] Session-2 script
Message-ID: <20090108235228.mssqahmg74kggg8o@webmail.mit.edu>

Friends--
Attached is a brief program script demonstrating use of several J features to
manipulate a character array representing a crossword puzzle.  You may copy it
directly into the j602-user section of your Documents, or paste it into a New
ijs window, then Save.

The strategy of computing marker flags for particular data values is an
important one for controlling subsequent operations on a whole collection.

The Rank adverb (") is the directive most frequently used to control function
application, but Insert is also used often.  The less popular Cut applies
functions to patterns within data lists.

I would like to hear what type of application you are thinking of tackling, so
that I may be able to present something relevant to it.
--Art Anger


From Anger at MIT.EDU  Sat Jan 10 11:57:59 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Sat, 10 Jan 2009 11:57:59 -0500
Subject: [J-learn] Getting into J
Message-ID: <20090110115759.pxpwubujsz4sswgs@webmail.mit.edu>

Class--
If you're learning from the "Primer", most of the material in Checkpoint A and
the first half of the material in Checkpopint B should be rather familiar now. 
Next to study are the first part of Checkpoint D and all of Checkpoint E.

In "Learning J", you should be somewhat acquainted with Parts 1 and 2, and
starting to explore Chapters 17 and 18.  (Part 6 gets into numerical work.)

I rediscovered this week that the standard installation sets a read-only status
on script files.  You can turn editability on and off with a keystroke, or you
can change the default via the Edit menu's Configure item.  You may also change
the screen's background color, and the type size or boldness.  (I have not found
much benefit from changing to other typeface families.)

When you start exploring supplied scripts, you may find it convenient to define
in your j602-user directory an alias for the j602 directory.
--Art Anger


From Anger at MIT.EDU  Wed Jan 14 22:02:20 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Wed, 14 Jan 2009 22:02:20 -0500
Subject: [J-learn] Session 3: Array-element selection
Message-ID: <20090114220220.4aetu1zycwi88kos@webmail.mit.edu>

Notes from Class 3 attached.
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From Anger at MIT.EDU  Thu Jan 22 07:28:46 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Thu, 22 Jan 2009 07:28:46 -0500
Subject: [J-learn] Data-reporting programs
Message-ID: <20090122072846.ip4vd06rpy80sgsk@webmail.mit.edu>

Attached is the (corrected) script for student reports, discussed in Session 5.
--AA
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From Anger at MIT.EDU  Fri Jan 23 23:20:20 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Fri, 23 Jan 2009 23:20:20 -0500
Subject: [J-learn] Session 6 and symbol aliases
Message-ID: <20090123232020.0b0x111dx6e8ocos@webmail.mit.edu>

Students--
Attached are two scripts, one covering the array restructuring of the last
class, and the other my version of names for symbols.
--Art Anger
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From Anger at MIT.EDU  Wed Jan 28 17:06:25 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Wed, 28 Jan 2009 17:06:25 -0500
Subject: [J-learn] Session 7
Message-ID: <20090128170625.a3926px3q3kgo008@webmail.mit.edu>

Students--
After resting up from last night's contra dance and two sessions of shoveling
snow, then slush, I found that my primary error in yesterday's program
execution was having brought an earlier version of the script.  Attached is the
newer version, and a minor extension of "Aliases".

After loading Contras, run (from menu or by pasting) the last statement of the
script to display the execution record.
--Art


From Anger at MIT.EDU  Fri Jan 30 17:36:39 2009
From: Anger at MIT.EDU (Arthur Anger)
Date: Fri, 30 Jan 2009 17:36:39 -0500
Subject: [J-learn] Sessions 7 & 8 and future
Message-ID: <20090130173639.lxwz8yhdnmn4kocg@webmail.mit.edu>

Students--
I did rest on Wednesday, but must not have been fully awake when I sent my
message without the attachments.

I have already attached scripts named Contra and Aliases.  The former makes
extensive use of the "literate" definitions in the latter, in the hope that
they will reduce the level of mental gymnastics involved in reading (and
writing) program scripts.  Familiarity with these names does not greatly assist
with reading the examples in the Vocabulary definitions and Dictionary Phrases. 
(It is rumored that APL and J are better accepted in Japan precisely because
they do not rely much on words.)

The Contra script shows examples of all three function-definition formats: 
multi-line and one-line explicit definitions, in which arguments appear by
name, and implicit definitions consisting of verb trains.  Arguments enter
implicit definitions only through standard verb association (often through
Right or Left, and through the magic transport of hook or fork interpretation),
and any other parameters must be bound or conjoined to verbs (explicitly!).

The goal in designing the programs was to enable direct execution of sequences
of defined words closely approximating typical phrases used to direct
contra-dancers.  The argument-pipeline approach used here offers fair
flexibility, but is not the only approach that might be used.  More elaborate
implementations could analyze a wider variety of text input in one or more
passes to determine what to execute.

The data manipulations in this script illustrate a variety of generation,
selection, and restructuring actions, useful in many fields of application. 
Use of strictly numerical functions should be easily managed by those who need
them.   A fruitful option, particularly convenient in J, is that of applying
numerical calculations to determine index positions or to produce intricate
logical-selection patterns.

If you have seen all that you care to see about J, you may unsubscribe from the
mailing list.  If you later have relevant questions, send them to me;  if you
suspect that other students may be in a similar quandary, write to me via the
class list, and I'll reply there.  If you're really hooked on the subject,
browse all the supplied Help areas, and items in the Books list in the JWiki
section at JSoftware.Com;  Iverson's "Math for the Layman" is not merely good
for describing J but also for analyzing how mathematicians and other scientists
should approach their work.

Best wishes, and do let me know when you find J useful to you.
--Art
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